Investigation of band alignment between AlN and atomic-layer-deposited ZrO2 by X-ray photoelectron spectroscopy

Abstract

The band alignment between AlN and atomic-layer-deposited ZrO2 was investigated by X-ray photoelectron spectroscopy (XPS). The dependence of Al 2p core-level positions on the take-off angle θ indicated upward band bending at the AlN surface. On the basis of angle-resolved XPS measurements combined with numerical calculations, the valence band of ZrO2 was found to be 0.23 ± 0.2 eV below that of AlN by taking the AlN surface band bending into account. By taking the band gaps of ZrO2 and AlN as 5.6 and 6.2 eV, respectively, a type-II energy band alignment with the conduction band discontinuity ΔEC of 0.83 ± 0.2 eV was found between ZrO2 and AlN.